I met this same error today and I guess you're trying to use event gen to do the scripted input, right? if so, you need to put an eventgen.conf file under you app/default folder. this works for me. You can have a try.
BTW, you can move eventgen/lib/eventgendefaults to your app/default folder and rename it as eventgen.conf.
Or just move it:
mv ...../lib/eventgendefaults ....app/default/eventgen.conf